Cutoff cylinder spring construction



sept. 11, 1951 C, s, CRAFTS 2,567,364

CUTOFF CYLINDER SPRING CONSTRUCTION Filed DeG. 15, 1947 Cuv-t i s 4S.Cv'cxts (jh-ra ram e,

Patented Sept. 11, 1951 UNITED l s'rATEs PATENT yoFElcE CIVITOVFFCYLDERSPRING CONSTRUCTION Curtis VStlraits, Oak Park, Ill., assignorto The-Goss Printing Press Company, Chicago, Ill., a corporation of Illinois Al ApplicationDecember 13, 1947,Y Serial No.'- 791-,586` l i iclaim, (ci.164-61A The present invention relates to printing presses and' morevparticularly toanl improved spring for use in a cut-on cylinder.

In conventional presses the cut-oft cylinderincludes a radialcuttingblade which is=longitudi nally mounted in the cylinder and is bo-undedon each side by a series ofblocks or' cheekwoods which are'biasedfoutwardly,l serving'tov hold the webs in place during the cuttingoperation. 'Ihe servicev performed by the cut-offV cylinder is extremelysevere since modern presses are designed to produce up to 50,000newspapers or more per hour, the cheekwoodsbeing depressed each time thecutis made. When running at such'high speed,v particularlywhere'a lar-genumber of webs are` run together andfolded prior to" cut-off, it hasbeen' necessary to replace the Acheekvvood biasing springs whichlbecomebroken, often after only a few hours of use. In an attempt to correc-tthis diili'culty, coil springs v`of various designs h-ave been'developed: over. the years which have been conservatively'designed fortheicalculated loading and displacement. Breakage has, however,"continued to be a chronic` fault of a modern -press and has beenconsideredv one'ofthe penalties paid for high press output.

Itis a prim-ary objectof the present invention to provide an improvedsprin'g'f-or a cutoi cylinderf which is adaptedfor use with cylinders ofconventional design and' which resists excessive strain and consequentbreakage in' spite of `re peated and severe impacton the cheekwoods.

It is another object to provideV an improved spring whichY issoconstructed that cocking or tilting of` the associated' cheekwood'does not causeexcessive strain and' which is ableA to withstand theloading applied. theretoV over a Wide range ofV press speeds andin spiteof considerable variation in the thicknessof the newspaper being`severed;

It is a further object to provide'a spring which is particularly Wellyadapted forindividual use with av cheekwood and in whichVV the spacebelow the cheekwood morefefliciently used for resillent storage andpartial absorption ofthe energy conveyed to the spring asa result offrceexerted'v on the cheekwood; It is a related object to provide aspring inherently adapted to equalize the pressuresappliedto the'ends ofa cheekwood in spite of limited longitudinal'tilting.

Itis a still further object to provide an improved spring'for a' cut-offcylindenwhich not only enables a substantialfreduction in spring expensebut which enables'rthe construction of the cutting assemblyl includingvthe knife bar to be considerably simpliedi- Other objectsandadvantagesof the invention will be apparent irmrthes detaileddescription taken. in connection withA the accompanying drawings, inwhich:

Figure 1I isv a fragmentary sectionalview of the cutting cylinder vshowingthe cutting blade, knife bar andV cheekwoods in cooperativerelation with the improved'spring'construction.

Fig. 2 is a section view takenalong line 2-2 of Fig. 1.

Fig. 3 is a cross-sectionalv view of the leaf spring construction takenalong line 'i3-3f of Fig. 2.

Fig; 47 is a detailed enlarged view ofthe'improved spring constructionVand withfthe' spring clamp in partial section. y

While the invention is susceptible'of`various modifications andalternative constructions arid uses, I have shown in the `drawing andvs'rill'herein describe in detail'one 'embodiment of the invention. Itis to be understood, however; thatI do' not intend to` limit theinvention by suchdis'- closure, but aim to coverall modifications andalternative constructionsV and uses falling within the spiritand scopeofthe inventonas expressed in the appended claims; f

Referring now'to'Figure lithe cut-oli cylinder indicatedl generally Y'at I0 has a longitudinal channel II'machined therein in'which ismountedthe cutting 'assembly I2; Suchcuttin'g assembly includes a' knife bar I4which extends the length of the groove and whichmounts a 'knife I5.knife bar may be rigidly fastened'in the groove IIV by any desiredlmeans,"for example, by means of a Wedge block or gib I6 which` presses'against a tapered surface I8 on theknife bar. In turn, the Wedge block'I5 is' retained in place'by a series of screws I1 which are spaced atintervals along the length of the bar. The knifev bar-is preferablyformedof Vtwo opposed L-shaped sections held together by bolts flla anddeflning'a longitudinal channel I9 within which the knife I5 islaterally centered. Although the` knife is rigidly fastened intlie'knifebari1 it may be' radially adjusted priorto being clamped inplace. The knife I5 thus divides the channel I9 into two spaces or`grooves'llla and I9b`. n

Lying within the grooves 'I'9a, I9b are the cheekwoodsY 20", 2|. lSuch,cheekwoods have rounded uppersurfaces 20a; 2 Ict'V respectively, butotherwise generally 'rectangular'in shape and arranged to slide looselywithin the spaces provided. Asshown to better advantage in' Fig. 2, thecheekvvoods are relatively shorty "conventionally abouty four or rive"inches in length and; are

The cutting assembly and'in particular: the Y axially separated by aclearance of approximately 11, inch as indicated at 24. During normaloperation of the press the cheekwoods are forced radially outward, bothas a result of centrifugal force and as a result of spring pressure.Outward movement is, however, limited by a plurality of cheekwoodretaining pins or dowels 25 which extend across the channel I9 of theknife bar I2 and through apertures 2E in the cheekwoods. These aperturesare radially elongated or slotllke so that considerable movementispermitted, the arrangement allowing one end of the cheekwood to beconsiderably depressed independently of the other end.

In accordance with the present invention an improved leaf springconstruction is provided relatively simple change of construction,conbelow each of the cheekwoods for biasing the same outwardly which isinherently adapted forVl the storage of a maximum amount of energy andwhich', at th'esame time, is not roverstrainedby serious tilting orcocking of the cheekwood. In the present instance the improvedspring-'indicated generally at 30 includes a'pluralityof'leaves -3h32,33, 34 and 35 which are graduatedin size andl which are prestre'ssedso'as to assume' a normal bowed shape.. The'spring -is arranged in thespace provided so uas to be concave upwardly, and the ends of thelargest of the leaves, namely leaf 3|, are flat or even reversely bentto provide a smoothabutting surface 38, 39 near .theends of the-cheekwood 20.' 1'

'I'he leaves are bundled together to form acomvpound'funitary spring bymeans of-av clamp 40. This clamp is provided with inwardly turned tabs4I, 42, as shown in F.ig.3,r which are pressed `inwardly after theleaves are assembled within .the U-shaped clamp body. In order Vtoprevent yrelative 'movement between the leaves, each of -them has aconvex offset portion at its center which mates With'correspondingportions on the adjacent leaves as indicated at44. Similarly, the clamp40 may include an internal dimple to 'mate with the offset centerportion of the leaf 35, the smallest in theseries. Y

In accordance with one of the .aspects of the 'invention means areprovided for maintaining the improved spring 30 axially centered underthe cheekwood'ZI) Vwith which it cooperates, while allowing the spring alimited amount of rotational freedom so that it may accommodate itselfto .cooking movement of the cheekwood. rlhatis to say, a restrainingmeans is provided which allows the spring to bodily teeter-totter underthe cheekwood through a limited angle. In the present instance 'this isaccomplished by providlng the clamp 40 with a downwardly extending lugor pin 46 which mates with an oversized hole 48 in the bottom of thechannel I9 of the knife bar. the clamp 40 may be made convex asdisclosed in Figs. 2 and 4 to permit limited rocking of the spring 30.

As a result of the above-outlined construction, .it has been possible tooperate printing presses for extended periods at the highest letterpress speeds lwithout objectionable breakage of the springs. In certaintests the improved springs operated satisfactorily at the end of atwelve week test period whereas conventional coil springs had failed inthe identical type of service in less than one week of operation. Thisis obviously advantageous, not only because of the Yreduction in springcost but also because of the saving of time on the part of the pressoperator who normally must shut the press down periodisiderable efforthas been spent to determine the reasons for the. successful operationand to uncoverl the basically new principles inherent in f the disclosedspring. In order to fully appreciate If desired, the bottom surface 49of the improvement it is t'necessary to understand rthat modern pressesoperate at a speed of'approximately 50,000' papers per hour whichcorresponds to a cutting rate of aboutfourteen operations per second ormore. Since the cutoff cylinder andthe cylinder with which itcooperatesare both nonyielding, the' effect isithe same as fourteen hammerblowsapplied to lthe cheekwoods each second over long periods of pressoperation.

To complicate matters such blows are not applied in a manner to causethe cheekwood to be `moved flatly inward but are applied in a mannerwhich frequently causes severe up-ending or cocking of the cheekwoods.The reason for this is that newspapers are madeupofa 'large number ofWebs which are runI 'together and foldedV prior to being led'into thecutter.` The thickness of the paper is generally considerably vgreaterat the fold than it is.' several inches distant from the fold.Accordingly, as the cut-oil? cylinder rotates the aifectedv cheekwoodinto contact with the folded portion of the paper, an impact is impartedto the cheekwood from the fold or high point ofthe paper. This causesone end of the cheekwood' to be driven radially inward to a much greaterextent than the 'opposite end of such cheekwood. In addition, otherminor irregularities caused by'accumulations of ink and paper dust, forexample, may result in the cheekwood being forced inwardly in a cockedposition.

In the conventional 'construction employing coil springs, the spring isrecessed over a considerable portion of its length in a hole drilled inthe bottom of the knife bar channel I9. Relatively few loops of the coilspring are therefore unguided or free-floating. As a; result, thecompression of the spring combined with Ithe 'cocking of the cheekwoodcauses the force to be ap- Aplied'to the spring at an angle to thespring axis. A careful study of broken springs removed from conventionalcut-off cylinders indicates that the upper loops or convolutions of thespring are forced againstthe'V mouth of the hole in which the springisreceive'd; and therefore, assume the greater share of the loading.A Asa result of the non-axial concentrated stress, breakage takes placegenerally inthe upper portion offv the spring. Y' i' f l Still anotherfactor which causes breakage of conventional springs' is the fact'thatbottoming occurs, in other words, at'least a portion of tl'ley adjacentspring convolutions are forced into contact with one another therebyVproviding an unyielding rather than a resilient stop for the cheekwoods.Such bottoming combined with non-axial loading canl be readilydemonstrated to cause pinching of one or two spring convolutionsresulting in severe localized stress and consequent breakage. This is tobe contrasted with the improved spring disclosed herein in whichbottoming is substantially impossible since the spring in its fullypressed or iiattened condition coincides dimensionally with the chan,mnel in which it is received. Furthermore, movement of the cheekwoodthrough the full range permitted by the slotted apertures 26 therein maytake place without running any danger whatsoever that the spring will besuddenly convertedl into a non-resilient abutment as is the case withconventional coil springs.

Particularly noteworthy is the operation of the present spring underconditions causing end-toend tilting or cocking of the cheekwood. Asstated above, the engagement between the lug e8 of the spring 38 and thecooperating hole Q8 in the knife bar is suiiciently loose to permitcorresponding tilting of the spring through a limited angle. If, forexample, the left-hand portion of the cheekwood 28 (Fig. 2) is deflectedinwardly to a greater extent than the right-hand portion, a greaterforce tends to be applied to the spring at the surface 38 than isapplied at the opposite end of the spring at surface 39. However,instead o the two halves of the spring acting independently, acompensating eiect sets in: As the left-hand portion of the spring istilted downwardly, the right-hand portion is free to move upwardlythrough a limited arc. As a result, the cantilever mounting of thespring is angled so that the left-hand portion is stressed to a lesserextent than it otherwise would be. This eiect occurs only through alimited angle, however, in the preferred construction since, uponfurther downward movement of the left-hand portion of the cheekwood,engagement occurs between the lug 48 and the walls of the cooperatinghole 48. Any excessive downward displacement of the lefthand portion ofthe spring is, therefore, increasingly resisted by the resultingcantilever deflection of the spring. In operation as the cheekwoodrotates into contact with the cylinder which cooperates with the cut-01Tcylinder, inward movement is resisted to an extent which is dependent,to a large extent, upon the average amount of inward movement.l There issubstantially no danger of breaking a spring even when a particularlyheavy fold is encountered by one of the associated cheekwood.

It has been stated above that a limited amount of bodily tilting of thespring may take place upon cocking of the cheekwood with which itcooperates. An advantage is inherent in this feature which deservesspecic mention. The spring as a result of such construction isinherently selfequalizing, that is, in normal operation the amount offorce exerted at the surface 38 is substantially the same as thatexerted by surface 39. Thus, as long as the cheekwood 20 remainsrelatively coaxial with the cut-oli" cylinder, all portions of thespring will be stressed uniformly. This situation is considerablydiierent from that in which a plurality of coil springs are used and inwhich any non-uniformity in the length or restoring characteristics ofsuch springs causes a single spring to absorb more than its share of theload with the obvious possibility of breakage.

Tests have also shown that the success of the spring may be due toconsiderable extent to the energy storage and absorptioncharacteristics. Any spring is inherently an energy storing device, andit is necessary to increase the thlckness o a spring of any type untilthe stress-strain ratio is such as to produce the desired restoringforce. This has, in the past, made is necessary to increase the wiresize so that a maximum amount of energy could be stored in a smallvolumetric space, with the result that the springs have been relativelystiff and inexible. As a result of using the present construction, itwill readily be seen that the spring, lying longitudinally under itscooperating cheekwood, utilizes the available space i'oi energy storingpurposes to a much greater degree than is possible with a coil spring oreven a series oi' coil spings. n other words, the irnproved springutilizes the available space for energy storage purposes more eicentlythan any other spring construction of which I am aware. And, since onlyone spring is required per cheekwood, the construction reduces thenumber of parts and thereby makes the cutting assembh7 much cheaper toconstruct, assemble, and maintain. The knife bar may be more cheaplyconstructed since only a small number of relatively shallow holes d8need be provided.

With regard to the energy absorption it will be apparent to one skilledin the art that the present leaved construction provides a large rubbingsurface both between adjacent leaves and at the areas 38, adjacent thecheekwood. This produces a snubber-like action which tends to reducerebound of the cheekwood thereby increasing the life of both thecheekwood and the spring itself. Any tendency toward overtravel of thecheekwood due to impact is substantially eliminated.

I claim as my invention:

A printing press cut-o cylinder having a knife bar defining alongitudinal outwardly facing channel, a cutting blade centered in saidchannel, a series of cheekwoods lying in said channel on each side ofsaid blade with means for limiting the outward movement of saidcheekwoods, a bowed leaf spring arranged in said channel under each ofsaid cheekwoods, each of said leaf springs having a plurality oflaminations in rubbing contact with one another, each of said leafsprings being symmetrically arranged under the associated cheekwood andhaving at its ends bearing surfaces for pressing engagement with the endportions of the underside of the associated cheekwood for rubbingthereagainst when the cheekwood is depressed, and means at the center ofeach of said springs for maintaining the spring in a iixed positionlongitudinally of said channel while permitting limited rocking movementof the spring` bodily in the channel in response to cocking of thecheekwood.

CURTIS S. CRAFTS.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 379,857 Cave et al Mar. 20, 18881,975,350 Davis Oct. 2, 1934

